Grounding grids

[rezaa]

Dear members,

After having a multilayer soil model assume we want to analyze ground impedance, GRP, touch voltage and step voltage for a large ground grids(lets say 1000 m * 1000 m), are the following assumptions the only ones we need or are there any other assumptions?

1- All conductors belonging to a given electrode are not at the same potential. There are potential drop along conductors due to their self-impedance. This means that the conductors modelled are not assumed to be lossless.

2- The mutual inductance of conductors needs to be taken into consideration.

Thanks,

Reza

 

[rezaa]

CDEGS does not take into account the multilayer soil models to simulate the circuit models associated with the grids. Are you aware of any software that take this matter into account while modeling the girds?

 

[jghrist]

The full CDEGS package will account for multilayer soil as well as potential drop along grid conductors. There are two separate grounding design modules, MALT and MALZ. MALT is low-frequency only and assumes that all conductors of a system are at the same potential (although you can model multiple unconnected systems). MALT can be purchased in 2-layer or multilayer versions. MALZ can handle higher frequencies and takes potential drop into account. MALZ is multilayer.

 

[jbartos]

Suggestion: Visit

http://www.powerearth.com.au/cdegs.htm

http://gpr-expert.com/software.htm

etc. for more info

 

[jghrist]

Back to the original post, there are numerous values that either need to be determined or assumed in order to analyze a ground grid. More numerous than can be listed here. I highly recommend getting a copy of IEEE Std 80-2000, IEEE Guide for Safety in AC Substation Grounding. See

http://shop.ieee.org/store/default.asp?tabtype=stand